<!DOCTYPE html>
<html>
<head>
</head>
<body>
<div id="foo1" class="foo"></div>
<code>
<div id="foo2" class="foo"></div>
<div id="foo3" class="foo"></div>
</code>
<pre id="out"></pre>
<script>
var elements = document.querySelectorAll("code .foo");

try {
    if (elements.length !== 2)
        throw 1;
    if (elements[0].id !== "foo2")
        throw 3;
    if (elements[1].id !== "foo3")
        throw 4;
    document.getElementById('out').innerHTML = "Success!";
} catch (e) {
    document.getElementById('out').innerHTML = "Error number " + e;
}

</script>
</body>
</html>
